Flaps or flap segments located on the wings of a commercial aircraft are usually extended or retracted by means of a drive system, which comprises drive stations that are distributed inside the wings and connected to the flaps or flap segments through adjustment levers or other devices. Often, drive stations are operated through receiving rotational power from one or more drive units, which are also known as “Power Control Units” (PCU), by means of a transmission shaft that extends from the PCU into the respective wing of the aircraft. The drive stations thereby convert a rotary motion into a translatory motion. Each connection between the PCU and a drive station thereby constitutes a so-called load path through which the respective flap or flap segment can be moved and arrested. Such a drive system may also be used for moving slats or slat segments.
As the deployment of control surfaces is necessary for the operation of the aircraft, various failure cases need to be considered. Instead of designing main elements of the drive station for bearing higher loads usually mechanical load limiters are installed. In a load limiter, the individual load path extends through a pretensioned clutch with a ball ramp device that opens by being pushed apart if a predetermined maximum torque is exceeded.
For achieving a certain level of redundancy, commonly a mechanical coupling between adjacent flaps supports moving the flap that is located beyond the shaft break is provided. Consequently, when the coupling is used, the arising torque is much higher than for moving a single adjustment lever. Therefore, the design of the drive stations and the structure of the control surface is appropriately adapted. By providing a mechanical coupling between adjacent flaps it may become impossible to integrate a function for a differential flap setting.
DE 103 13 728 discloses a drive station that includes two drives connected via drive transmissions to one or more flaps or slats of a flap/slat group. The drives may be mechanically coupled to a rotational shaft, with a shaft brake arranged thereon.
Further, a skew detection system for use in sensing the occurrence of a skew condition in a system having a plurality of control surfaces is know, which comprises a linear detector arrangement extending over and movable with the surfaces between a first location on one of the surfaces and a second location on another of the surfaces, being connected to sensors that are able to detect a pulling force.